Synthesis, crystal structure and magnetic properties of a mixed-valence pentanuclear cobalt complex

Abstract

Solvothermal reaction of Co(OAc)2.4H2O with H4L (H4L = 2-((2-hydroxybenzylidene)amino)-2-hydroxymethylpropane-1,3-diol) in MeCN gave a mixed-valence pentanuclear cobalt complex [Co5(HL)2(H2L)2(OAc)2].2.5H2O. Crystal structural analysis revealed that two Co(III) ions were linked to a central triangular Co(II) core through HL(3-) and H2L(2-) hydroxyl groups. Magnetic measurements showed interesting magnetic properties that were assigned to spin-orbital coupling and ferromagnetic exchange interactions.

Transition metal complexes of a versatile polyalkoxy oxazolidine-based ligand derived fromin situcyclization

“…[5][6][7][8][9][10][11] One of the popular ways to design new polyalkoxy ligands is through Schiff-base condensation between hydroxyaldehydes and aminoalcohols. [12][13][14][15][16][17][18][19][20][21][22][23] In line with our interest in designing new polynuclear coordination complexes for studying magnetic and biomimetic properties, we coupled 8-hydroxyquinoline and tris(hydroxymethyl)aminomethane to design the desired Schiff-base ligand H 4 L 1 (Scheme 1). However, the reaction between 8-hydroxyquinoline-2-carboxaldehyde (HQC) and tris(hydroxymethyl)aminomethane (TRIS) yielded an oxazolidine derivative by in situ cyclization, and produces H 3 L 2 during the synthesis.…”

Synthesis, structure, and properties of a pentanuclear cobalt(III) coordination cluster

“…Self-assembly of this type of dinuclear complex via formation of additional bridges by the ancillary ligands of the primary dinuclear unit or by small bridging ligands can lead to extended polynuclear coordination clusters involving additional metal cations [13][14][15][16][17]. The magnetic properties of cobalt(II) have led to considerable interest in cobalt(II) coordination clusters as single molecule magnets [10,11,[17][18][19][20][21][22][23][24][25]. In an attempt to prepare a coordination cluster using cobalt(II) acetate and the acyclic compartmental Schiff base 2,6-bis((3-aminopropylimino)methyl)-4-methylphenol, we have isolated the diamagnetic pentanuclear cobalt(III) species…”

Synthesis and magnetic properties of a new hexanuclear iron(III) compound

“…As part of our interest in searching for high-nuclearity metal clusters, we have recently synthesized a OH-rich Schiff-base ligand and investigated the magnetic properties of its cobalt cluster [4]. The present work focuses on the ligand 2-((1,3-dihydroxy-2-methylpropan-2-ylimino)methyl)phenol (H 3 DHMP, Scheme 1), which has four functional groups that can bridge metal ions resulting in high nuclearity clusters.…”

“…Among them, most iron(III) clusters are those involving oxygen bridges, such as oxo-, hydroxo-, alkoxo-and phenolato-bridges, and are achieved from ligand-assisted hydrolysis and/or alcoholysis of iron(III) ions. These bridges usually propagate antiferromagnetic interactions between iron(III) ions and thus for a given Fe x cluster with x an even number its ground state would be zero, although sometimes spin frustration may occur and leads to non-zero ground state.As part of our interest in searching for high-nuclearity metal clusters, we have recently synthesized a OH-rich Schiff-base ligand and investigated the magnetic properties of its cobalt cluster [4]. The present work focuses on the ligand 2-((1,3-dihydroxy-2-methylpropan-2-ylimino)methyl)phenol (H 3 DHMP, Scheme 1), which has four functional groups that can bridge metal ions resulting in high nuclearity clusters.…”